Everybody can volunteer to help Doctors Without Borders. In order for someone to help out, he/she can simply go to DWB's website under the topics "Work with Us" or "Support Us":
http://www.doctorswithoutborders.org/support-us . Otherwise, donate money, spread the word, attend events and fundraisers. DWB benefits all kinds of communities because if people in each town donate money, DWB can use that money to help citizens in other areas. The money provided can help people all across the world. Everybody's donation, no matter how big or small, can make a difference.